Unroll strided loop

src/targets/gpu/kernels/include/migraphx/kernels/functional.hpp

@@ -118,6 +118,12 @@ constexpr auto sequence_c_impl(F&& f, seq<Ns...>)
     return f(index_constant<Ns>{}...);
 }
 
+template <class F, index_int... Ns>
+constexpr void repeat_c_impl(F f, seq<Ns...>)
+{
+    swallow{(f(integral_constant<index_int, Ns>{}), 0)...};
+}
+
 template <index_int... N>
 constexpr auto args_at(seq<N...>)
 {
@@ -144,6 +150,18 @@ constexpr auto sequence(IntegerConstant ic, F&& f)
     return sequence_c<ic>(f);
 }
 
+template <std::size_t N, class F>
+constexpr void repeat_c(F f)
+{
+    detail::repeat_c_impl(f, detail::gens<N>{});
+}
+
+template <class IntegerConstant, class F>
+constexpr auto repeat(IntegerConstant ic, F&& f)
+{
+    return repeat_c<ic>(f);
+}
+
 template <class F, class G>
 constexpr auto by(F f, G g)
 {

src/targets/gpu/kernels/include/migraphx/kernels/index.hpp

@@ -27,6 +27,7 @@
 #include <migraphx/kernels/hip.hpp>
 #include <migraphx/kernels/types.hpp>
 #include <migraphx/kernels/integral_constant.hpp>
+#include <migraphx/kernels/functional.hpp>
 #include <migraphx/kernels/type_traits.hpp>
 
 namespace migraphx {
@@ -63,8 +64,9 @@ struct index
     template <class F, class N, class Stride>
     static constexpr void for_stride(index_int start, N n, Stride stride, F f)
     {
-        if constexpr(not is_integral<N>{} and not is_integral<Stride>{} and
-                     max_stride_iterations(n, stride) == 1)
+        if constexpr(not is_integral<N>{} and not is_integral<Stride>{})
+        {
+            if constexpr(max_stride_iterations(n, stride) == 1)
             {
                 if constexpr(stride > n)
                 {
@@ -77,6 +79,13 @@ struct index
                 }
             }
             else
+            {
+                repeat(max_stride_iterations(n, stride), [&](auto i) {
+                    f(start + stride*i);
+                });
+            }
+        }
+        else
         {
             for(index_int i = start; i < n; i += stride)
             {